Emergent Magnetic Monopoles at Room Temperature Controlled

A three-dimensional (3D) network in solid-state physics promises a new era. This network could have many applications in photonics, bio-medicine, and spintronics. 3D magnetic nano-architectures are possible to create ultra-fast, low-energy data storage devices. These systems can produce magnetic monopoles or charges due to competing magnetic interactions. These can then be used as mobile binary information carriers. Researchers from the University of Vienna have created the first 3D artificial spin ice lattice that hosts unbound magnetic charges. These results, published in the journal npj Computational Materials, provide the first theoretical demonstration of how external magnetic fields can control magnetic monopoles.

In a class called spin ices, emergent magnetic monopoles can be observed. Their controllability is limited by their atomic scales and the need for low temperatures. This resulted in the creation of 2D artificial spun ice. Here, single atomic moments have been replaced by magnetic nano-islands arranged on different lattices. This allowed for the study of emergent magnet monopoles on larger platforms. The reverse magnetic orientation of nano-islands enables the monopoles to be propagated one vertex further. This leaves a trace. The Dirac Strings, or path, store energy and bind the monopoles to limit their mobility.

Sabri Koraltan, Florian Slanovc, and Dieter Suess, the University of Vienna researchers, have created a 3D artificial ice lattice combining the best atomic and 2D spin ices.

The benefits of the new lattice have been studied in cooperation with Nanomagnetism and Magnonics group at the University of Vienna and the Theoretical Division of Los Alamos Laboratory (USA) using micromagnetic simulations. Magnetic rotational Ellipsoids have replaced flat 2D nano-islands. A high-symmetry, three-dimensional lattice has also been used. Sabri Koraltan is one of the first authors of this study. Researchers took their survey to the next level. They used external magnetic fields to simulate one magnetic monopole propagating through the lattice. This demonstrated its potential as an information carrier in a 3D magnetic network.

Sabri Koraltan says, “We use the third dimension, high symmetry, in the new lattice to unbind magnetic monopoles and move them in the desired direction almost like true electrons.” Florian Slanovc, the other first author, concludes, “The thermal stability of the monopoles at room temperature or above could lay the foundations for a groundbreaking new generation 3D storage technologies.”